Tier 2 Arlington Area Bacteria and Flow Source Investigation

Transcription

1 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum Prepared for: SAWPA MSAR TMDL Task Force Prepared by: Amec Foster Wheeler Environment & Infrastructure, Inc. San Diego, California January 2018 Amec Foster Wheeler Project Number:

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3 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force TABLE OF CONTENTS Page Acronyms and Abbreviations... ii 1.0 Purpose Study Approach Monitoring Results Western Subdrainage Area (ARL-1) Central Drainage Area (ARL-2) Western Drainage Area (ARL-3) Analysis and Discussion Key Findings Limitations of Data Next Steps References LIST OF FIGURES Figure 1. Study Area... 5 Figure 2. Summary of Results and Flow by Site Figure 5. Flow Comparison by Land Use Figure 3. E. coli Concentrations by Land Use Type Figure 4. Summary of HF183 Results by Land Use Type Figure 6. Summary of Key Findings LIST OF TABLES Table 1. Study Approach... 3 Table 2. Monitored Events... 7 Table 3. Profile of Flow and Bacteria in the Eastern Subdrainage Area (ARL-1)... 9 Table 4. Profile of Flow and Bacteria in the Central Subdrainage Area (ARL-2) Table 5. Profile of Flow and Bacteria in the Western Subdrainage Area (ARL-3) Table 6. Summary of Flow Data Table 7. BMP Recommendations Table 8. Identify Sources of Flow Table 9. Continue Bacteria Source Investigation LIST OF ATTACHMENTS Attachment A: Bacteria and Flow Source Inventories Attachment B: Field Data Forms and Representative Photographs Attachment C: Field and Analytical Data Attachment D: Flow Estimates Attachment E: Study Plan Page i

4 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force ACRONYMS AND ABBREVIATIONS 303(d) list Amec Foster Wheeler CBRP CCTV CWA DNQ Clean Water Act Section 303(d) list of water quality impaired segments Amec Foster Wheeler Environment & Infrastructure, Inc. Riverside County Comprehensive Bacteria Reduction Plan closed-circuit television Clean Water Act quantification limit E. coli Escherichia coli EPA GIS gpm HF183 mg/l ml MPN/100mL MS4 MSAR MST SARWQCB SAWPA SCCWRP TMDL TSS United States Environmental Protection Agency geographic information system gallons per minute human marker milligrams per liter milliliters most probable number per 100 milliliters municipal separate storm sewer system Middle Santa Ana River microbial source tracking Santa Ana Regional Water Quality Control Board Santa Ana Watershed Project Authority Southern California Coastal Water Research Project Total Maximum Daily Load total suspended solids Page ii

5 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force 1.0 Purpose Santa Ana River Reach 3 is on the Clean Water Act (CWA) 303(d) list of water quality impaired segments (303(d) list) because of elevated indicator bacteria concentrations (Santa Ana Regional Water Quality Control Board [SARWQCB], 2005a) and has also been subject to the Middle Santa Ana River (MSAR) Bacteria Indicator Total Maximum Daily Load (TMDL), Resolution R , since its approval by the United States Environmental Protection Agency (EPA) in 2006 (SARWQCB, 2005b). To comply with the requirements of the MSAR Bacteria Indicator TMDL, an MSAR Watershed TMDL Task Force (Task Force; Santa Ana Watershed Project Authority [SAWPA], 2013) was formed by urban and agricultural dischargers to implement routine TMDL compliance monitoring and upstream source investigations in the MSAR (SAWPA, 2016). Upstream source investigations are triggered based on routine monitoring data and follow a tiered approach. Tier 1 source investigations and preliminary follow up work performed by the City of Riverside (2016) identified the Arlington Area as a potential contributor to downstream bacteria exceedances. The City of Riverside s preliminary work also found elevated Escherichia coli (E.coli) and evidence of dry weather flows from nearby agricultural land uses. The differentiation between flow and bacteria sources by land use is important with respect to the regulations in the TMDL and source control or implementation actions. For these reasons, the MSAR Watershed TMDL Task Force selected the Arlington Area 1 for a Tier 2 Bacteria Source Investigation. This investigation supports the MSAR and Riverside County Comprehensive Bacteria Reduction Plan (CBRP) Framework, which is designed to address controllable urban sources of bacteria by Municipal Separate Storm Sewer System (MS4) Permittees only (SAWPA, 2013). Step 1 of the CBRP Framework is to identify, prioritize, and evaluate MS4 dry weather flow sources and then consider appropriate best management practices (BMPs) in Steps 2 and 3 (SAWPA, 2013). Amec Foster Wheeler Environment & Infrastructure, Inc. (Amec Foster Wheeler) completed a preliminary bacteria and flow source investigation in the Arlington Area on behalf of the Task Force. The investigation sought to answer the following study questions: What is the status of dry weather flow leaving the Monroe Retention Basin? What are the predominant sources of dry weather flow in the Arlington Area? What are the magnitude and sources of E. coli in observed dry weather flow? Are the observed E. coli from human sources? This technical memorandum summarizes the Tier 2 investigations of bacterial contamination and dry weather flow in the Arlington Area, and includes a brief review of the study approach, summary of monitoring data, key findings, and next steps. 1 The Arlington Area is located in the City of Riverside. Land uses are predominantly agricultural and urban. Page 1

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7 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force 2.0 Study Approach This study was designed to provide a snapshot of late dry season conditions in the Arlington Area, and to provide a preliminary assessment of the spatial and temporal extent of bacteria and flow sources. Study goals include distinguishing contributions from agricultural and mixed land uses and identifying persistent and intermittent 2 sources of bacteria and flow and prioritizing areas for potential BMPs or additional source investigation as-needed. With regard to bacteria source identification, human sources are considered highest priority, because animal sources are generally of lower risk to human health (Soller et al., 2010). Table 1 summarizes the study approach for the Tier 2 source investigation. Study Question What are the predominant sources of dry weather flow in the Arlington Area? What are the magnitude and sources of E. coli in the observed dry weather flow? What is the status of dry weather flow leaving the Monroe Retention Basin? Are E. coli from human sources? Any recommendations? Notes: HF183 = human marker; MST = microbial source tracking Table 1. Study Approach Data Analysis Estimate flow at each site monitored. Estimate the relative contributions from different land uses by comparing flow from the predominantly agriculture land use sites with the flow from the three main points of discharge that include both the agricultural and urban land uses. Perform a field survey to track sources of observed flows. Characterize the spatial extent of bacteria throughout the Arlington Area. Use water quality data, visual observations, and flow data in the context of the bacteria source inventory to develop a profile of the three distinct subdrainage areas within the Arlington Area. Estimate dry weather flows discharging to the basin using continuous flow data from the three sites in the Monroe Retention Basin. Confirm the status of flows leaving the Monroe Retention Basin and the status of flows reaching the Santa Ana River (at T1-ANZA). Use HF183 data to identify known versus suspected presence of human sources. Assess HF183 data in the context of documented bacteria sources. Expand the source inventory to support prioritization of sources. Prioritize the three subdrainage areas (and locations within each) for further investigation, and provide recommendations for next phase of field investigations. Recommendations may include testing archived samples for additional MST markers. Based on the MS4, the Arlington Area was subdivided into three distinct subdrainage areas, (eastern [ARL-1], central [ARL-2], and western [ARL-3]). Each of these three subdrainage areas represents mixed land uses from both residential/commercial and agricultural land uses. Monitoring locations were established at a major storm drain outfall at the base of these three subdrainage areas at the point of discharge to the Monroe Retention Basin. Additionally, based on geographic information system (GIS) analysis and field reconnaissance, monitoring locations were selected to isolate inputs from predominantly agricultural land use within each subdrainage area. Lastly, one monitoring location was selected within the Gage Canal to characterize irrigation 2 Persistent sources are present in all three monitored events, whereas intermittent sources are recorded one or two events of the three. Page 3

8 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force source water prior to its application to agricultural land uses and to support evaluation of water quality into context of the source water. Continuous dry weather flow monitoring was a critical component of the study design. Continuous flow was collected for a four-week period to generate a profile at the base of each the three subdrainage areas within the late dry season. The flow data are a key factor in determining which drainage area is contributing the most dry weather flow to Monroe Retention Basin and may be a higher priority for follow-up investigations. These data can be used to identify patterns of dry weather flow, including peaks when inspections or investigations should be targeted. Three monitoring events were used to distinguish persistent from intermittent flows and levels of bacteria. When flow was present at an identified monitoring location, visual conditions and field measurements were recorded and a sample was collected and analyzed for analytical parameters, including total suspended solids (TSS), E.coli and a human microbial source tracking (MST) marker. Figure 1 presents a schematic of the study area and the three distinct subdrainage areas within the Arlington Area. Page 4

9 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Note: Drainage areas are approximate. Figure 1. Study Area Page 5

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11 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force 3.0 Monitoring Results This section summarizes monitoring activities and data generated during the Tier 2 investigation. Bacteria and flow source inventories per subdrainage area are provided in Attachment A. Field data forms and representative photographs are provided in Attachment B. Analytical laboratory reports are provided in Attachment C. Flow estimates and hydrographs are provided in Attachment D. The Study Plan is provided in Attachment E. The Tier 2 investigation was conducted primarily in September Field visual surveys were also conducted on August 18, 2017, and October 2, 2017, to identify potential sources of bacteria within each drainage area and to identify areas where flows and sources were absent. These observations were compiled on maps of the individual watersheds and are provided in Attachment A. Three dry weather monitoring events were conducted on September 11, 13, and 18, 2017 in accordance with the Study Plan (SAWPA, 2017) requirements (antecedent dry period of 7 days with no measureable rainfall). Visual observations were completed during each event to record bacteria (e.g., presence of domestic animals, vegetation/debris) and flow (e.g. residential overirrigation, grove irrigation) sources. In addition to general visual survey for flow and bacteria sources, flows observed at monitoring locations were followed within the public right-of-way to their origins via street-level tracking. A summary of monitored events is provided in Table 2. Drainage Area NA Site Type Table 2. Monitored Events Site Names 9/11/17 (n) Monitored Events 9/13/17 (n) 9/18/17 (n) Control Site Gage Irrigation Canal (GIC) Flowing (1) Flowing (1) Flowing (1) Eastern Central Western Agricultural (Ag) Land Use Adams Street (ADA) Dry Dry Dry Jefferson Street (JEF) Dry Dry Dry Grace Street (GRC) Flowing (1) Dry Dry Madison Street (MAD) Dry Dry Dry Washington Street (WAS) Ponded (1) Dry Dry Mixed (Ag and Urban) Land Use ARL-1 Flowing (1) Flowing (1) Flowing (1) Ag Land Use Gratton Street (GRA) Flowing (1) Flowing (1) Flowing (1) Mixed Land Use ARL-2 Flowing (1) Flowing (1) Flowing (1) Irving Street (IRV) Flowing (1) Dry Dry Ag Land Use Monroe Street (MON) Flowing (1) Dry Dry Mixed Land Use ARL-3 Flowing (1) Flowing (1) Flowing (1) Arlington Area Monroe Basin Outlet OUT Flowing SNR Flowing SNR Flowing SNR Anza Discharge point of Anza Channel ANZA Flowing SNR Flowing SNR Notes: n= number of samples collected when water was present; NA = not applicable; SNR = sample not required. Flowing SNR Page 7

12 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force A total of 21 water quality samples were collected during the three dry weather monitoring events. Three samples were collected from the Gage Irrigation Canal to assess water quality of grove irrigation water prior to application. Nine samples were collected from the eight agricultural land use sites. Nine samples were collected from the three mixed land use sites. All samples were submitted to Babcock Laboratories 3 within holding times for analysis of TSS, E. coli, and HF183 4 (human marker). Key flow and bacteria results by subdrainage area are provided in Sections 3.1 through 3.3 and in Figure Western Subdrainage Area (ARL-1) ARL-1 had continuous flow during the study period. ARL-1 had the lowest flow rates (mean flow 14.1 gallons per minute [gpm]) of the three inputs to Monroe Retention Basin. Of the five agricultural land use sites identified within this subdrainage area, only two sites flowed 5 during one monitored event during the study period. Field crews were not able to confirm the flows were from agricultural parcels or uses. For one of the observed instances of flow at an agricultural site, the flow source was suspected to be recent residential irrigation. Based on the study period, the agricultural sites were deemed not to be the main source of dry weather flows to ARL-1. Visual surveys did not record evidence of surface flows within the urban land use during the sampling period. Further investigation within the subsurface MS4 system is needed to determine other potential sources of the dry weather flows. Agricultural flows captured by this investigation may be under-representing typical contributions during the dry season. This drainage area in particular may benefit from more targeted sampling based on the grove irrigation schedule and monitoring over the entire dry season. Four of five samples in the ARL-1 subdrainage had E. coli concentrations above the SSM: one of two samples from agricultural sites, and three of three samples from mixed land use sites. E. coli concentrations ranged from MPN/100mL and were the lowest of the three subdrainage areas. No quantifiable HF183 marker was detected in samples from agricultural sites. One of three samples at the mixed land use monitoring location had quantifiable HF183 marker (133 copies/100ml). Field crews observed domestic animals, trash, organics 6, and birds at monitoring locations in this subdrainage area. Table 3 provides key sampling results for the ARL-1 subdrainage. Figure 2 provides water quality and flow condition data for the ARL-1 subdrainage. 3 For analysis of HF183, Babcock Laboratories processed and archived samples on dry ice within holding times per the Study Plan, and then shipped samples to Source Molecular for additional DNA analysis (HF183). 4 HF183 is a human-associated microbial source tracking (MST) marker. 5 One sample was collected from ponded water (recent flow). 6 Organics include vegetative debris, algae or similar materials. Page 8

13 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Table 3. Profile of Flow and Bacteria in the Eastern Subdrainage Area (ARL-1) Flow Persistent flow at Monroe Retention Basin 2 of 5 Ag sites had contributing to MS4 during 1 of 3 events 3 of 5 Ag sites had no flow Bacteria 4 of 5 samples exceed E. coli SSM. When Ag sites flow, they contribute E. coli to the MS4 One sample from mixed land use had quantifiable HF183 Observed organics, domestic animals, birds, and trash Data Gaps Source of dry weather flows in urban land use Agricultural flow contributions during scheduled grove irrigation ARL-1 Ponded Residential Irrigation 3.2 Central Drainage Area (ARL-2) ARL-2 had continuous flow during the study period. Flows were generally highest (mean flow gpm) of the three inputs to Monroe Retention Basin. One agricultural land use site was identified at Gratton Street within this subdrainage area, which flowed during three of three monitoring events at a rate ranging from 32.8 to 41 gpm. Field crews confirmed the flows were from grove irrigation for two of three monitored events; for the third event, grove irrigation was suspected but not able to be confirmed. These findings were consistent with the City of Riverside s previous field reconnaissance. The agricultural site is a dominant source of dry weather flows to ARL-2. Visual surveys were recorded evidence of surface flows within the MS4 area during the sampling period. Further investigation within the subsurface MS4 system are needed to determine other potential sources of the dry weather flows. Five of six samples in the ARL-2 subdrainage had E. coli concentrations above the SSM: two of three samples from agricultural sites, and three of three samples from mixed land use sites. No quantifiable HF183 marker was detected in samples from agricultural sites. One of three samples at the T2-ARL-2 monitoring location had a quantifiable HF183 marker (226 copies/100ml). Field crews observed domestic animals, trash, and birds at monitoring locations in this subdrainage area. Table 4 provides key sampling results for the ARL-2 subdrainage. Figure 2 provides water quality and flow condition data for the ARL-2 subdrainage. Page 9

14 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Table 4. Profile of Flow and Bacteria in the Central Subdrainage Area (ARL-2) Flow Persistent flow at Monroe Retention Basin Persistent flow at Ag site Ag site is considered a dominant source of flow Bacteria 5 of 6 samples exceed E. coli SSM. When Ag sites flow, they contribute E. coli to the MS4. One sample from mixed land use had quantifiable HF183 Observed domestic animals, birds, and trash Data Gaps Sources of dry weather flows in urban land use ARL-GRT Grove Irrigation 3.3 Western Drainage Area (ARL-3) ARL-3 had continuous flow during the study period. Flows were higher than ARL-1 but lower than ARL-3 (mean flow 31.4 gpm). Two agricultural land use sites at Irving and Monroe Streets within this subdrainage area had intermittent flows (each flowed during two of three events) during the study period. The agricultural sites are a dominant source of dry weather flows to ARL-3: for example, the second monitored event on 9/13/17 had the highest flow rates at the input to Monroe Retention Basin when both upstream agricultural sites were flowing. Visual surveys did not record evidence of surface flows within the urban land uses during the sampling period. Further investigation within the subsurface MS4 system are needed to determine other potential sources of the dry weather flows. Six of seven samples in the ARL-3 subdrainage had E. coli concentrations above the SSM: three of four samples from agricultural sites, and three of three samples from mixed land use sites. Of all three subdrainage areas, E. coli concentrations were highest (75->24,000 MPN/100mL) in ARL-3. However, ARL-3 was the only subdrainage area with no quantifiable HF183 in any in samples from either agricultural sites or mixed land use sites. Field crews observed domestic animals, trash, organics, chickens, and birds at monitoring locations in this subdrainage area. Table 5 provides key sampling results for the ARL-3 subdrainage. Figure 2 provides water quality and flow condition data for the ARL-3 subdrainage. Page 10

15 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Table 5. Profile of Flow and Bacteria in the Western Subdrainage Area (ARL-3) Flow Persistent flow at ARL-3 Intermittent flow (2 of 3 events) at both Ag sites, confirmed as grove irrigation Ag sites considered a dominant source of flow Bacteria 6 of 7 samples exceed E. coli SSM. When Ag sites flow, they contribute E. coli to the MS4 No quantifiable HF183 in drainage area despite highest levels of E. coli of all subdrainages Observed organics, domestic animals, birds, chickens, and trash Data Gaps Source of dry weather flows in urban land use ARL-3 Monroe Street Figure 2 presents the water quality and flow conditions for each site that had observed flow during the study period and depicts the relationship between the agricultural and mixed land use sites per subdrainage area. Page 11

16 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Notes: DNQ = detected but not quantifiable (detected below the reporting limit); ND = not detected 1. Instantaneous flow rate associated with time of upstream instantaneous flow estimate. See Table D-1 for more information. Figure 2. Summary of Results and Flow by Site Page 12

17 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force 3.4 Analysis and Discussion As described in Table 2 and Sections 3.1 through 3.4, the three inputs to Monroe Retention Basin had continuous flow for the duration of the study period. Flow rates at ARL-2 were generally highest (mean flow gpm), followed by ARL-3 (mean flow 31.4 gpm). Flow rates at ARL-1 (mean flow 14.1 gpm) were much lower than flow rates at ARL-2 and ARL-3. Sampling events at the three inputs to Monroe Retention Basin captured a representative range of flow conditions. At ARL2, where flows were generally highest, flows at time of sample collection ranged from 4.3 to gpm. Flows at time of sample collection for ARL-1 and ARL-3 were 7.4 to 24.4 gpm and 2.3 to gpm, respectively. Attachment D provides the estimated flows associated with each sample collected. Of the nine samples collected at mixed land use sites (inputs to Monroe Retention Basin, downstream of both urban and agricultural land uses), seven samples were affected by active flows from upstream agricultural sites at the time of sample collection. Two of these seven samples were also affected by active or recent residential over-irrigation at the time of sample collection. Active upstream sources of flow could not be identified for two samples. Instantaneous flows were estimated at upstream agricultural sites; if a site had flow during all three events, the flow was considered persistent. If a site had flow during two or fewer events, then the flow was considered intermittent. Of the eight agricultural land use sites visited, one site had persistent flow, four sites had intermittent flows, and three sites had no flow during the monitored events. To evaluate relative contributions of flow from agricultural land uses, the downstream instantaneous flow rate associated with the time of the flow estimate at the upstream location was extracted from the continuous flow data record. Additional detail is provided in Attachment D. A summary of flow rates by site is provided in Table 6. Inputs to Monroe Retention Basin Table 6. Summary of Flow Data Flow Rates at Time of Upstream Sample Collection 1 (gpm) Upstream Agricultural Flow Rates at Time of Sample Collection 1 (gpm) 9/11/17 9/13/17 9/18/17 Sites 9/11/17 9/13/17 9/18/17 T2-ARL ARL-1-ADA ARL-1-JEF Dry Dry ARL-1-GRC <1 2 Dry Dry ARL-1-MAD Dry ARL-1-WAS 0 3 Dry Dry T2-ARL ARL-2-GRT T2-ARL ARL-3-IRV Dry ARL-3-MON Dry 60.7 <1 2 Notes: 1. Time of sample and flow estimate collection differs by site; therefore, instantaneous upstream and downstream flow values are not directly comparable. To enable comparison, a representative time point for flow rates at downstream sample locations was determined based on upstream sample collection times and an assumed minute flow travel time. Table D-1 provides more information. 2. Trickle flow observed. 3. Ponded water observed. Suspected to be from recent residential over-irrigation 4. Active residential over-irrigation observed in urban land use at time of sample collection. Page 13

18 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Of the nine instances of flow (or recent flow) observed at the five agricultural input monitoring locations with intermittent or persistent flows, six of the sources were tracked to their origin and were confirmed as grove irrigation (Attachment A). Two samples had unidentified sources; grove irrigation was suspected because of the quantity of flow and general origin, but could not be confirmed in the field because the private property was inaccessible (Attachment A). One sample (ponded) was suspected to have originated from residential over-irrigation, based on evidence of recent flow (Attachment A). In the urban land use area between the agricultural inputs and the Monroe Retention Basin, residential over-irrigation was observed to be actively contributing to downstream sites during one instance. Preliminary assessment of relative contributions from different source types to the Monroe Retention Basin is summarized in Figure 5. As summarized in Figure 5, flows at upstream agricultural inputs were often attributable to agricultural grove irrigation. The intermittent nature of irrigation sources of flow, compared with the persistent nature of flow at downstream inputs to the Monroe Retention Basin, suggests that some flow may be originating from sources yet to be characterized, such as residential irrigation, additional illicit discharges, groundwater, or illicit connections. Additional data are needed. However, when flows from agricultural inputs (grove irrigation) were actively occurring, they did contribute most of the flow observed at the downstream input to the Monroe Retention Basin for the ARL-2 and ARL-3 subdrainage areas, which represent the majority of flow to the Monroe Retention Basin. Page 14

19 Instantaneous Flow Rate (gpm) Instantaneous Flow Rate (gpm) Instantaneous Flow Rate (gpm) Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force ARL ARL-2 ARL-3 Event 1 (9/11/17) Event 2 (9/13/17) Event 3 (9/18/17) Total from Mixed (Ag + Urban) Land Use Agricultural Land Use Urban Land Used Note: Where agricultural instantaneous flow rates exceed mixed land use instantaneous flow rates, this does not necessarily represent infiltration, detention, or evaporation. Rather, the flow rate may attenuate as the flow moves downstream. Cumulative flow comparisons from paired continuous flow data collection will provide more quantitative and accurate comparisons. Figure 5. Flow Comparison by Land Use Page 15

20 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Field water quality measurements were typically within normal environmental ranges. Several samples from agricultural input sites had elevated ammonia concentrations (>1 milligram per liter [mg/l]) during the September 11, 2017, monitoring event. However, the elevated values were likely attributable to elevated ammonia concentrations in source irrigation water that day: a value of mg/l was observed in a sample from the Gage Irrigation Canal, and flows at the agricultural locations were caused by active grove irrigation. No samples had ammonia concentrations greater than 2 mg/l. Elevated free chlorine (>0.3 mg/l) was also observed in some samples. Elevated chlorine in samples from mixed land uses may be reflective of inputs from residential over-irrigation. However, elevated chlorine was also observed in some agricultural inputs. The agricultural inputs with elevated chlorine were field verified as coming from grove irrigation. Elevated chlorine was not present in the grove irrigation source water from Gage Canal. These data suggest that chlorine may be introduced during application of water to groves, or that potable water may be being used for grove irrigation. Attachment B provides the field water quality measurements associated with each sample collected. Similar to findings from the City of Riverside s field reconnaissance (City of Riverside, 2016), E. coli concentrations were variable, but generally increased as flows moved from the upper, predominantly agricultural land uses to the lower, mixed land uses of the Arlington Area, and both agricultural and urban land uses contributed E. coli to dry weather flows. None of the source irrigation water from the Gage Canal had E. coli concentrations above the single-sample maximum 7 (SSM) of 212 organisms per 100 milliliters (organisms/100ml). The majority of agricultural sites (six of nine samples), had E. coli concentrations above the SSM. All samples from mixed land use sites (T2-ARL-1, T2-ARL-2, T2-ARL-3) had detected E. coli concentrations above the SSM. Figure 3 provides box plots of E. coli concentrations by site type. Increases in E. coli concentrations as flows moved from upstream locations to downstream locations indicate additional inputs; because of the short travel times within the small subdrainage areas, evaporation is not considered to be a significant factor. HF183 was not detected in most (19 of 21) samples. Two samples with HF183 were low level ( copies per 100mL) and recorded at mixed land use sites. For reference, HF183 concentrations in raw municipal sewage are typically greater than one million (>10 6 ) copies/100ml. These low level detections may indicate the presence of a human source in the urban land use portion of the drainage area (e.g. leaking sewer infrastructure), or a false detection due to a cross-reaction from an animal source (e.g. chicken or dog). Because low-level human signals still have the potential for public health significance (SCCWRP, 2017), it is appropriate to investigate these low-level detections as a conservative measure. No agricultural sites had quantifiable HF183. Attachment C provides E. coli and HF183 concentrations associated with each sample collected. Figure 4 provides a summary of HF183 results by site type. 7 TMDL compliance targets for E. coli state that not more than 10% of the samples exceed 212 organisms/100ml for any 30-day period (SARWQCB, 2005b). For the purposes of this Tier 2 source investigation, 212 organisms/100ml was used an a single-sample maximum. Page 16

21 E. coli (MPN/100mL) E. coli (MPN/100mL) Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force n = 3 n = 9 n = 9 Gage Gage Canal Canal Predominantly Predominantly Ag Ag Mixed Mixed Ag Land + Urban Use Irrigation Sourcewater Land Use Land Use Min Outlier Max Outlier Note: The box represents the interquartile range (IQR). The ends of the whiskers are set at 1.5*IQR above the third quartile and below the first quartile. Outliers are outside of this range. Figure 3. E. coli Concentrations by Land Use Type This te whiske whiske quartile quartile values shown box plo simplify outliers each d the cha NOTE: interqu positiv display other w data w - Addin additio column Sample series - Addin Figure 4. Summary of HF183 Results by Land Use Type Page 17

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23 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force 4.0 Key Findings Key findings in the context of the study questions are as follows: What is the status of dry weather flow leaving the Monroe Retention Basin? Dry weather flow is continuous both into and out of the Monroe Retention Basin. Continuous flow data collected at the three storm drain inputs to the basin indicate persistent flow at all inputs. o Flow volumes at T2-ARL-1 are much lower than flow volumes at either T2-ARL-2 or T2-ARL-3. Visual observations at the basin outlet and the T1-ANZA monitoring location indicate persistent flow leaving the basin and reaching the Santa Ana River (see Table 2). What are the predominant sources of dry weather flow in the Arlington Area? Based on instantaneous flow estimates and visual observations, when flow is present, agricultural discharges contribute most of the flow reaching the Monroe Retention Basin. Magnitude of flow in each subdrainage area corresponded with the occurrence of flow at agricultural inputs; the subdrainage areas where flow from agricultural inputs is most frequent (ARL-2 and ARL-3) have flow rates typically two to six times higher than at ARL-1, where agricultural flows were observed at one of five inputs during one event. However, persistence of flow at the outfall was not always attributable to active agricultural irrigation. o o Other flow sources (e.g., residential over-irrigation) are present and contribute flow to the storm drain. The persistence of flow may also suggest other sources not observed during the streetlevel survey (e.g., illicit discharges, groundwater, illicit connections). What are the magnitude and sources of E. coli in the observed dry weather flow? E. coli was quantified in all dry weather flows sampled within the Arlington Area. E. coli does not originate from the Gage Irrigation Canal. E. coli concentrations were elevated in flows from agricultural land uses as well as mixed (urban and agricultural) land uses. Magnitudes generally increased in flow moving from upstream to downstream locations (accumulation of sources). Multiple potential human and nonhuman sources of bacteria were observed in the drainage area. Sewer lines, septic systems, grove irrigation, livestock, domestic animals, wildlife, trash, and vegetation/sediment were observed in all subdrainage areas (Attachment A). Portable toilets were observed in ARL-1 only, and residential over-irrigation was observed in ARL-2 and ARL-3 only. These sources were observed, but not assessed as actively impacting dry weather flows. Page 19

24 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Is the observed E. coli from human sources? The majority of samples do not contain E. coli from human sources. o o o HF183 was not quantified in 19 of the 21 samples Human sources are not contributing to flows originating from the agricultural inputs based on the general absence of detectable HF183. Human sources were observed in flows originating from the mixed land use inputs, but concentrations were relatively low. Human sources may potentially contribute to flows from mixed land use inputs but require additional confirmation. For the two samples in which HF183 was quantified: o o Detections were in one (of two) samples from each of two different mixed land use monitoring locations, indicating that potential human contamination is episodic and not persistent. Concentrations in both samples were <300 copies/ml. For reference, raw municipal wastewater typically contains 10 6 copies/100ml. 4.1 Limitations of Data The following limitations apply to the data collected for this investigation: The investigation took place during approximately one month in the late dry season and may not be representative of year-round conditions. Sampling was not coordinated directly with the grove irrigation schedule. Instantaneous flow estimates represent point-in-time conditions and do not provide a comprehensive assessment of relative contribution. Monitoring data was not collected within the MS4 system (only at either end). Flow leaving the Monroe Retention Basin co-mingles with other dry weather inputs before reaching the Santa Ana River. It is unknown how much of the flow leaving the basin ultimately reaches the Santa Ana/River. Low-level, intermittent detections of a single human marker do not provide sufficient information to establish risk to human health. Per the California Source Identification Manual, the HF183 marker is the best starting point for detecting human fecal material because it provides the best combination of sensitivity and specificity. However, although it performs highest among other markers on sensitivity, it has been shown to occasionally detect ( crossreact with) chicken or dog feces. If those sources pose a concern in the watershed, or if managers simply desire to add certainty about the results, HF183 can be paired with HumM2. (Southern California Coastal Water Research Project [SCCWRP], Because low-level concentrations may still be risk-relevant (SCCWRP, 2017) due to aged or diluted sources, confirmation of potential human sources is desired. Page 20

25 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Figure 6. Summary of Key Findings Page 21

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27 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force 5.0 Next Steps Based on findings to date, Amec Foster Wheeler recommends the following next steps to address identified sources of flow, increase understanding of bacteria sources, and enhance the current study design to quantify identified and suspected flow sources. This study has confirmed that dry weather flow from the MS4 is continuous both into and out of the Monroe Retention Basin. This study also confirmed that grove irrigation from agricultural land uses is contributing flow and bacteria to the MS4 system in the Arlington Area, though grove irrigation is not the sole contributor. Controlling or reducing flows both in upstream agricultural land uses and downstream urban land uses will help reduce bacteria loads to/from the Monroe Retention Basin. There are options to reduce dry weather flows through implementation of management and structural BMPs. Table 7 presents BMP recommendations for the Arlington Area. Table 7. BMP Recommendations BMP Implementation in Agricultural Land Uses BMP Implementation in Urban Land Uses Implement retention or infiltration BMPs on agricultural parcels where grove irrigation was confirmed to be contributing dry weather flow and elevated bacteria concentrations to the MS4 Implement infiltration BMPs at Monroe Retention Basin Retrofit Monroe Retention Basin to perform dry weather retention Increase inspection of right of ways and notify parcel owners of runoff Increase residential and commercial inspections This study identified a comprehensive list of sites to capture potential dry weather flows from agricultural land uses. However, there were agricultural sites that did not flow during the study period or only intermittently. To characterize flows at each agricultural site throughout the dry season, then additional targeted monitoring is needed. Additionally, some sources of flow remain unknown. Table 8 presents recommendations to target and further investigate flow sources to Monroe Retention Basin. Page 23

28 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Table 8. Identify Sources of Flow Flows from Ag Sources Flows from Other Sources Targeted sampling based on grove irrigation schedule Visual observations during dry season at varying times of day. Increase monitored events and inspect sites throughout the dry season Survey of storm drains to investigate illicit connections or groundwater infiltration This study was the first step in characterizing the contribution of flow from agricultural sources to the downstream MS4. This initial study design paired continuous flow data from the MS4 inputs to Monroe Retention Basin with instantaneous flow estimates at the agricultural sites. To refine the analysis of contributions from agricultural sites, continuous flow data should be collected to enable the comparison of cumulative flow volumes. Similarly, if the Task Force wants to better understand the contribution from the Monroe Retention Basin to the T1-ANZA site and ultimately Santa Ana River, then paired continuous flow data and tracer studies should be performed to verify continuous flow status and confirm hydrologic connectivity. Multiple potential human and nonhuman sources of bacteria were observed in the drainage area. Sewer lines, septic systems, grove irrigation, livestock, domestic animals, wildlife, trash, and vegetation/sediment are present in all subdrainage areas (Attachment A). These sources were not assessed as actively impacting dry weather flows. This study determined that additional monitoring is needed to characterize urban sources. Based on the data, prioritize drainage basins for further source investigation including visual surveys and water quality. Within each drainage basin, add monitoring locations within the urban land use including MS4 catch basins representing residential and commercial land uses. For the next phase of investigation, reduce the water quality that is being recorded at each site for cost savings to E.coli, HF183 (depending on drainage area and Tier 2 results), ammonia, conductivity, and flow. This study assessed whether E. coli was originating from human sources. The HF183 human MST marker was used to screen for human sources. The HF183 marker is recommended by the California Source ID Manual (SCCWRP, 2013) as the most sensitive and specific human MST marker, and is the human marker the United States Environmental Protection Agency (USEPA) is developed a standard method for. The HF183 is conservative in that it has the potential to cross-react with dog or chicken feces in a sample. Thus, to add certainty to the assessment of human sources, it is recommended that the samples be analyzed for a second human MST marker, such as HumM2 (per the California Source ID Manual) or B. theta (per the QAPP) to add certainty to the findings. If the human source is not detected by a second marker, it is Page 24

29 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force recommended that BMPs focus on reductions in non-human bacteria sources (such as dog waste, via outreach and doggy bag stations). However, if the human source is confirmed by detection with a second human marker, further source investigation is warranted. Further source investigation includes review of potential human sources and their likelihood to contribute (e.g. review of sewer overflow records, sewer repair and maintenance records, septic system status and maintenance records) and collection of additional data. These low level detections may indicate the presence of a human source in the urban land use portion of the drainage area (e.g. leaking sewer infrastructure), or a false detection due to a cross-reaction from an animal source (e.g. chicken or dog).this study identified evidence of animals within the drainage areas. To evaluate potential bacteria contributions from animals, analyze the archived samples for both chicken and dog. Table 9 presents recommendations to further investigate E.coli, human sources and animal sources within the Arlington Area. Table 9. Continue Bacteria Source Investigation Page 25

30 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force 6.0 References City of Riverside Letter written by Michael Roberts to Mr. Ken Theisen. Monitoring of Agricultural Areas within the City of Riverside Greenbelt. Dated Nov 4, Santa Ana Regional Water Quality Control Board (SARWQCB). 2005a. Staff Report on Bacteria Indicator Total Maximum Daily Loads in Middle Santa Ana River. February 3, SARWQCB. 2005b. Resolution Amending the Water Quality Control Plan for the Santa Ana River Basin to Incorporate Bacteria Indicator Total Maximum Daily Loads (TMDLs) for Middle Santa Ana River Watershed Waterbodies. Regional Board Resolution R Santa Ana Watershed Project Authority (SAWPA) San Bernardino County Stormwater Program, County of Riverside, Cities of Chino Hills, Upland, Montclair, Ontario, Rancho Cucamonga, Rialto, Chino, Fontana, Norco, Corona, Riverside, Pomona, and Claremont Middle Santa Ana River Bacteria Indicator TMDL Implementation Report. Prepared by CDM Smith, February SAWPA Santa Ana River Watershed Bacteria Monitoring Program Quality Assurance Project Plan (QAPP). Prepared by CDM Smith, February SAWPA Tier 2 Bacteria Source Investigation Arlington Area Study Plan. Prepared by Amec Foster Wheeler. September Soller et al Estimated human health risks from exposure to recreational waters impacted by human and non-human sources of faecal contamination. Water Research. 44: Southern California Coastal Water Research Project (SCCWRP) The California Microbial Source Identification Manual: A Tiered Approach to Identifying Fecal Pollution Sources to Beaches. Technical Report 804. December. SCCWRP Southern California Bight 2013 Regional Monitoring Program: Shoreline Microbiology. Volume IX. Technical Report September. Page 26

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32 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Attachment A: Bacteria and Flow Source Inventories Page A-1

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34 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force For this investigation, a source inventory is a list of potential sources that may contribute flow, E. coli, and/or HF183 in the Arlington Area. For each of the three subdrainage areas, source inventories were developed to help interpret monitoring data and to prioritize follow-up investigative activities. Source inventories are intended to be updated as needed to capture additional monitoring data. The following data were used to develop preliminary source inventories prior to field activities: Desktop analysis of infrastructure (sewer, septic, recycled water, storm drain) and land use Field surveys (both pre-data collection and as part of monitoring activities) Review of historical data Correspondence with key stakeholders Source inventories were then updated to reflect field data collection. Source inventories by subdrainage area are provided in Table A-1. Results of flow source tracking specific to collected samples are provided in Table A-2. Detailed map-based source inventories for the Arlington Area are provided in Figures A-1 through A-3. Table A-1. Potential Sources of Bacteria and Flow in the Arlington Area Potential Bacteria Potential Present in Source Source? Flow Arlington Observation/Verification E. coli HF183 Source? Area? T2-ARL-1 T2-ARL-2 T2-ARL-3 Sewer Infrastructure Yes Yes Yes Yes Not assessed Recycled Water Infrastructure No Yes 1 Yes No Does not impact Arlington Area 5 Septic Systems Yes Yes Yes Yes Not assessed Potable Water Infrastructure No No Yes Yes Not assessed Rising Groundwater Yes Yes 2 Yes Unknown Not assessed Residential/Commercial Overirrigation Yes No 3 Yes Yes Not Observed Observed Observed Agricultural Over-irrigation Yes No 3 Yes Yes Observed Washing Yes No Yes Unknown Not observed Livestock Yes No No Yes Observed (horses and chickens) Portable Toilets Yes Yes Yes Yes Observed Not Observed Not Observed Illicit Discharges Yes Yes Yes Unknown Observed outside of the Arlington drainage area Illicit Connections Yes Yes Yes Unknown Not assessed Vegetation/Sediment Yes No No Yes Observed Domestic Animals Yes No 4 No Yes Observed (dogs) Wildlife Yes No No Yes Observed (birds) Trash Yes Yes No Yes Observed Notes: 1. Recycled water does not contain fecal indicator bacteria (FIB) but may contain human marker (Southern California Coastal Water Research Project [SCCWRP], 2017). 2. If contaminated by leaking sewer infrastructure or septic systems. 3. Fertilizer containing human biosolids has the potential to contribute based on origin, but has not been explicitly assessed. 4. There is potential for cross-reactivity of the HF183 marker with dog waste (SCCWRP, 2013). 5. Per personal communications with Brenda Meyer at Western Municipal Water District on 8/8/2017. Page A-3

35 -> Upstream to Downstream -> Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Table A-2. Key Flow Observations Site Type Irrigation Source Water Agricultural Inputs Mixed Land Use Inputs to Monroe Retention Basin Outlet of Monroe Retention Basin Site ID Key Visual Observations 9/11/17 9/13/17 9/18/17 T2-ARL-GIC Flowing Flowing Flowing T2-ARL-3-IRV T2-ARL-3-MON T2-ARL-2-GRT Flowing Confirmed Grove Irrigation No Flow Flowing Suspected Grove Irrigation Flowing Confirmed Grove Irrigation Flowing Confirmed Grove Irrigation Flowing Confirmed Grove Irrigation No Flow Flowing Confirmed Grove Irrigation Flowing Confirmed Grove Irrigation T2-ARL-1-ADA No Flow No Flow No Flow T2-ARL-1-JEF No Flow No Flow No Flow T2-ARL-1-GRC Flowing Suspected Grove Irrigation No Flow No Flow T2-ARL-1-MAD No Flow No Flow No Flow T2-ARL-1-WAS T2-ARL-1 T2-ARL-2 T2-ARL-3 T2-ARL-OUT Ponded Suspected Residential Over-irrigation Flowing Active contribution from upstream agricultural site Flowing Active contribution from upstream agricultural site Flowing Active contribution from upstream agricultural site No Flow Flowing Unknown upstream source Flowing Active contribution from upstream agricultural site and urban land use (residential over-irrigation) Flowing Active contribution from upstream agricultural site Flowing Input to Santa Ana River T1-ANZA Flowing Notes: Blue shaded cells indicate presence of ponded (light blue) or flowing (medium blue) water. No Flow Flowing Unknown upstream source Flowing Active contribution from upstream agricultural site Flowing Active contribution from upstream agricultural site Page A-4

36 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Note:Drainage area boundaries are approximated Figure A-1. Arlington Area ARL-1 Bacteria Source Inventory Page A-5

37 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Note: Drainage area boundaries are approximated Figure A-2. Arlington Area ARL-2 Bacteria Source Inventory Page A-6

38 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Note: Drainage area boundaries are approximated Figure A-3. Arlington Area ARL-3 Bacteria Source Inventory Page A-7

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40 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Attachment B: Field Data Forms and Representative Photographs Page B-1

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42 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Figure B-1. Site T2-ARL-1 Figure B-2. Site T2-ARL-2 Page B-3

43 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Figure B-3. Site T2-ARL-3 Figure B-4. Site T2-ARL-1-WAS Page B-4

44 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Figure B-5. Site T2-ARL-1-MAD Figure B-6. Site T2-ARL-1-GRC Page B-5

45 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Figure B-7. Site T2-ARL-1-JEF Figure B-8. Site T2-ARL-1-ADA Page B-6

46 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Figure B-9. Site T2-ARL-2-GRT Figure B-10. Site T2-ARL-3-MON Page B-7

47 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Figure B-11. Site T2-ARL-3-IRV Figure B-12. Site T2-ARL-GIC Page B-8

48 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Figure B-13. Site T2-ARL-OUT Figure B-14. Site T1-ANZA Page B-9

49 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Figure B-15. Grove Irrigation Figure B-16. Residential Over-irrigation Page B-10

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128 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Attachment C: Field and Analytical Data Page C-1

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130 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Table C-1. Analytical Results for Bacteria Sampling Event Date 9/11/17 9/13/17 9/18/17 Inputs to Monroe Retention Basin E. coli Concentration (MPN/100mL) Human Marker Concentration (copies/100ml) ARL ND Upstream Agricultural Sites E. coli Concentration (MPN/100mL) Human Marker Concentration (copies/100ml) ARL-1-ADA ARL-1-JEF ARL-1-GRC 210 ND ARL-1-MAD ARL-1-WAS ND 1 ARL ND ARL-2-GRT 98 ND ARL ND ARL ND ARL-3-IRV >24000 ND ARL-3-MON ARL-1-ADA ARL-1-JEF ARL-1-GRC ARL-1-MAD ARL-1-WAS ARL ND ARL-2-GRT ND ARL ND ARL ARL-3-IRV 230 ND ARL-3-MON 3100 <10 ARL-1-ADA ARL-1-JEF ARL-1-GRC ARL-1-MAD ARL-1-WAS ARL ARL-2-GRT 400 ND ARL ND ARL-3-IRV ARL-3-MON 74 ND Notes: Bolded values are in excess of applicable water quality objectives (WQOs). Gray shaded cells = site dry E. coli = Escherichia coli; J = estimated value, below limit of quantification; ml = milliliter; MPN = most probable number; ND = not detected; -- = not sampled because of lack of flow 1. Sample collected from ponded water. Notes Page C-3

131 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Sampling Event Date 9/11/17 9/13/17 9/18/17 Inputs to Monroe Retention Basin ARL-1 4 Table C-2. Analytical Results for TSS TSS (mg/l) Upstream Agricultural Sites TSS (mg/l) Notes ARL-1-ADA -- ARL-1-JEF -- ARL-1-GRC 10 ARL-1-MAD -- ARL-1-WAS ARL-2 2 ARL-2-GRT 40 ARL-3 4 ARL-1 2 ARL-3-IRV 36 ARL-3-MON -- ARL-1-ADA -- ARL-1-JEF -- ARL-1-GRC -- ARL-1-MAD -- ARL-1-WAS -- ARL-2 ND ARL-2-GRT 6 ARL ARL-1 ND ARL-3-IRV 22 ARL-3-MON 6 ARL-1-ADA -- ARL-1-JEF -- ARL-1-GRC -- ARL-1-MAD -- ARL-1-WAS -- ARL-2 4 ARL-2-GRT 4 ARL-3 4 Notes: Bolded values are in excess of applicable water quality objectives (WQOs). Gray shaded cells = site dry J = estimated value, below limit of quantification; mg/l = milligrams per liter; ND = not detected; -- = not sampled because of lack of flow. 1. Sample collected from ponded water. ARL-3-IRV -- ARL-3-MON 8 Elevated TSS concentration may be associated with collection of ponded flow using sterile syringe Page C-4

132 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Table C-3. Analytical Results for Gage Irrigation Canal (Irrigation Source Water Site ID Sampling Event Date TSS (mg/l) E. coli Concentration (MPN/100mL) Human Marker Concentration (copies/100ml) Notes T2-ARL-GIC 9/11/ ND None 9/13/17 ND 10 ND None 9/18/17 6 ND ND None Notes: Bolded values are in excess of applicable water quality objectives (WQOs). Gray shaded cells = site dry J = estimated value, below limit of quantification; mg/l = milligrams per liter; ND = not detected; -- = not sampled because of lack of flow. Page C-5

133 -> Upstream to Downstream -> Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Site Type Site ID Temp ( C) ph Table C-4. Summary of Field Water Quality Data Specific Conductivity (µs/cm) Turbidity (NTU) Ammonia (mg/l) Chlorine 1 (mg/l) Irrigation Source Water T2-ARL-GIC Agricultural Inputs Mixed Land Use Inputs to Monroe Retention Basin Outlet of Monroe Retention Basin T2-ARL-3-IRV T2-ARL-3-MON T2-ARL-2-GRT T2-ARL-1-ADA T2-ARL-1-JEF No Flow Not Sampled No Flow Not Sampled T2-ARL-1-GRC T2-ARL-1-MAD No Flow Not Sampled T2-ARL-1-WAS T2-ARL T2-ARL T2-ARL T2-ARL-OUT NR 2 Input to Santa Ana River T1-ANZA NR 2 Notes: 1. Total chlorine. 2. Not required per the Study Plan. 3. Both samples collected had ph of Though chlorine values were elevated in some samples, samples with elevated chlorine were confirmed in the field as originating from grove irrigation. Page C-6

134 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Attachment D: Flow Estimates Page D-1

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136 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Sampling Event Date 9/11/17 9/13/17 9/18/17 Inputs to Monroe Retention Basin Instantaneous Flow Estimate at Time of Sample Collection 1 (gpm) Instantaneous Flow Estimate Associated with Time of Upstream Instantaneous Flow Estimate 2 (gpm) Table D-1. Instantaneous Flow Estimates Upstream Agricultural Sites Instantaneous Flow Estimate (gpm) Sum of Instantaneous Flows from Agricultural Land Uses (gpm) Sum of Instantaneous Flows Observed in Urban Land Uses (gpm) Relative Contribution from Agricultural Land Uses ARL-1-ADA -- ARL-1-JEF -- ARL ARL-1-GRC Trickle (<1 gpm) 1 3,4 1 5 Minor ARL-1-MAD -- ARL-1-WAS Ponded ARL ARL-2-GRT Major ARL ARL-3-IRV 5.8 ARL-3-MON Major ARL-1-ADA -- ARL ARL-1-JEF -- None based on ARL-1-GRC instantaneous observations ARL-1-MAD -- ARL-1-WAS -- ARL ARL-2-GRT Major ARL ARL-3-IRV 4.6 ARL-3-MON Major ARL-1-ADA -- ARL ARL-1-JEF -- None based on ARL-1-GRC instantaneous observations ARL-1-MAD -- ARL-1-WAS -- ARL ARL-2-GRT Major ARL ARL-3-IRV -- ARL-3-MON Trickle (<1 gpm) Minor Notes: -- = not sampled because of lack of flow 1. Instantaneous flow estimates at time of sample collection obtained from continuous flow record. Instantaneous flows estimated in the field at these sites used as calibration points for continuous flow monitoring. 2. The sampling team collected samples and flow estimates at the inputs to Monroe Retention Basin before visiting upstream agricultural sites: the difference in sample collection times was typically 1-2 hours. Therefore, instantaneous flow estimates at time of sample collection at the inputs are not directly comparable with upstream flow estimates to assess relative contribution. A representative time point was determined based on upstream sample collection times and an assumed minute flow travel time, and the associated instantaneous flow value used for comparisons. 3. Trickle flows assumed to be 1 gpm for assessment purposes. 4. Suspected to be from agricultural over-irrigation, but not able to be field verified. 5. Ponded water observed at ARL-1-WAS suspected to be residential over-irrigation based on field observations. Assumed to be 1 gpm for assessment purposes. 6. Field verified as agricultural irrigation. 7. Two instances of recent residential over-irrigation observed. Each assumed to be 1 gpm for assessment purposes. Page D-3

137 Flow (gpm) Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force T2-ARL Wet Weather Event /1/2017 0:00 9/30/2017 0:00 9/29/2017 0:00 9/28/2017 0:00 9/27/2017 0:00 9/26/2017 0:00 9/25/2017 0:00 9/24/2017 0:00 9/23/2017 0:00 9/22/2017 0:00 9/21/2017 0:00 9/20/2017 0:00 9/19/2017 0:00 9/18/2017 0:00 9/17/2017 0:00 9/16/2017 0:00 9/15/2017 0:00 9/14/2017 0:00 9/13/2017 0:00 9/12/2017 0:00 9/11/2017 0:00 9/10/2017 0:00 9/9/2017 0:00 9/8/2017 0:00 9/7/2017 0:00 9/6/2017 0:00 9/5/2017 0:00 9/4/2017 0:00 9/3/2017 0:00 9/2/2017 0:00 9/1/2017 0:00 8/31/2017 0:00 8/30/2017 0:00 Orange line = Continuous flow data at T2-ARL-1; Purple dots = sum of Instantaneous flow estimates at upstream agricultural inputs. Figure D-1. Arlington Area Continuous Flow Date: Site T2-ARL-1 Page D-4

138 Flow (gpm) Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force T2-ARL Wet Weather Event Weir Malfunction{ /1/2017 0:00 9/30/2017 0:00 9/29/2017 0:00 9/28/2017 0:00 9/27/2017 0:00 9/26/2017 0:00 9/25/2017 0:00 9/24/2017 0:00 9/23/2017 0:00 9/22/2017 0:00 9/21/2017 0:00 9/20/2017 0:00 9/19/2017 0:00 9/18/2017 0:00 9/17/2017 0:00 9/16/2017 0:00 9/15/2017 0:00 9/14/2017 0:00 9/13/2017 0:00 9/12/2017 0:00 9/11/2017 0:00 9/10/2017 0:00 9/9/2017 0:00 9/8/2017 0:00 9/7/2017 0:00 9/6/2017 0:00 9/5/2017 0:00 9/4/2017 0:00 9/3/2017 0:00 9/2/2017 0:00 9/1/2017 0:00 8/31/2017 0:00 8/30/2017 0:00 Orange line = Continuous flow data at T2-ARL-2; Purple dots = Instantaneous flow estimates at upstream agricultural input. Weir malfunction occurred on September 28, 2017 due to large debris from upstream. Figure D-2. Arlington Area Continuous Flow Date: Site T2-ARL-2 Page D-5

139 Flow (gpm) Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force T2-ARL Wet Weather Event /1/2017 0:00 9/30/2017 0:00 9/29/2017 0:00 9/28/2017 0:00 9/27/2017 0:00 9/26/2017 0:00 9/25/2017 0:00 9/24/2017 0:00 9/23/2017 0:00 9/22/2017 0:00 9/21/2017 0:00 9/20/2017 0:00 9/19/2017 0:00 9/18/2017 0:00 9/17/2017 0:00 9/16/2017 0:00 9/15/2017 0:00 9/14/2017 0:00 9/13/2017 0:00 9/12/2017 0:00 9/11/2017 0:00 9/10/2017 0:00 9/9/2017 0:00 9/8/2017 0:00 9/7/2017 0:00 9/6/2017 0:00 9/5/2017 0:00 9/4/2017 0:00 9/3/2017 0:00 9/2/2017 0:00 9/1/2017 0:00 8/31/2017 0:00 8/30/2017 0:00 Orange line = Continuous flow data at T2-ARL-3; Purple dots = sum of Instantaneous flow estimates at upstream agricultural inputs Figure D-3. Arlington Area Continuous Flow Date: Site T2-ARL-3 Page D-6

140 Tier 2 Arlington Area Bacteria and Flow Source Investigation Technical Memorandum January 2018 SAWPA MSAR TMDL Task Force Attachment E: Study Plan (To be provided in PDF only) Page E-1

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142 Santa Ana Watershed Project Authority (SAWPA) Tier 2 Bacteria Source Investigation Arlington Area Study Plan Prepared by: Amec Foster Wheeler August 2017

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144 TABLE OF CONTENTS PAGE 1 INTRODUCTION PURPOSE PROJECT ORGANIZATION AND SCHEDULE SCHEDULE CONSTRAINTS STUDY AREA AND SITE SELECTION SITE SELECTION DRY WEATHER FLOW MONITORING CONTINUOUS FLOW MONITORING INSTANTANEOUS FLOW ESTIMATES E. COLI SOURCE STUDY MONITORING LOCATIONS SAMPLE COLLECTION VISUAL OBSERVATIONS FIELD WATER QUALITY ANALYSIS LABORATORY ANALYSIS MONITORING LOGISTICS AND QUALITY ASSURANCE AND QUALITY CONTROL (QA/QC) APPROACH FOR DATA ANALYSIS AND REPORTING REFERENCES SAWPA Arlington Tier 2 i August 2017 Study Plan

145 LIST OF TABLES Table 1. Points of Contact... 2 Table 2. Tentative Project Milestones and Deadlines... 2 Table 3. Continuous Flow Monitoring Locations and Equipment Configurations... 7 Table 4. Tier 2 Source Investigation Monitoring Locations... 9 Table 5. Field Water Quality Measurements...12 Table 6. Laboratory Water Quality Parameters...12 Table 7. Sample Handling and Holding Times...13 Table 8. Quality Assurance and Quality Control Samples...14 LIST OF FIGURES Figure 1. Tier 2 Source Investigation Monitoring Locations and Arlington Area Overview... 5 LIST OF ATTACHMENTS Attachment A Example Field Data Sheet SAWPA Arlington Tier 2 ii August 2017 Study Plan

146 LIST OF ACRONYMS AND ABBREVIATIONS µs/cm 303(d) list Bacteria TMDL C COC CV CWA ddpcr microsiemens per centimeter Clean Water Act Section 303(d) List of Water Quality Impaired Segments Resolution Amending the Water Quality Control Plan for the Santa Ana River Basin to Incorporate Bacteria Indicator Total Maximum Daily Loads (TMDLs) for Middle Santa Ana River Watershed Waterbodies. Regional Board Resolution R Celsius chain of custody coefficient of variation Clean Water Act E. coli Escherichia coli FDS ID L LA mg ml MPN MSAR MST NA NPDES NTU QA/QC QAPP RCFC&WCD RCP RL RPD SARWQCB SAWPA Site ID SM TMDL TSS WLA droplet digital polymerase chain reaction field data sheet identification liters load allocation milligrams milliliters most probable number Middle Santa Ana River microbial source tracking not applicable National Pollutant Discharge Elimination System nephelometric turbidity units quality assurance and quality control Quality Assurance Project Plan Riverside County Flood Control and Water Conservation District reinforced concrete pipe reporting limit relative percent difference Santa Ana Regional Water Quality Control Board Santa Ana Watershed Project Authority site identifier Standard Method Total Maximum Daily Load total suspended solids wasteload allocation SAWPA Arlington Tier 2 iii August 2017 Study Plan

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148 1 INTRODUCTION Santa Ana River Reach 3 was added to the Clean Water Act (CWA) 303(d) list of water quality impaired segments (303(d) list) in 1988because of elevated indicator bacteria concentrations (Santa Ana Regional Water Quality Control Board [SARWQCB], 2005a). The SARWQCB adopted the Middle Santa Ana River (MSAR) Bacteria Indicator Total Maximum Daily Load (TMDL), Resolution R (SARWQCB, 2005b) in August 2005 as an amendment to the Water Quality Control Plan for the Santa Ana River Basin (Basin Plan) (SARWQCB, 1994). The MSAR Bacteria Indicator TMDL became effective on May 16, 2007, and specified dry season wasteload allocations (WLAs) for point source discharges and load allocations (LAs) for nonpoint source discharges for fecal coliform and Escherichia coli (E. coli) in the MSAR water bodies, including the Santa Ana River. The MSAR Bacteria Indicator TMDL also required urban and agricultural dischargers in the area to implement a watershed-wide monitoring program, leading to formation of the MSAR Watershed TMDL Task Force (Santa Ana Watershed Project Authority [SAWPA], et al., 2013). A Quality Assurance Project Plan (QAPP) was developed and approved by SAWPA to support bacteria indicator monitoring activities, including routine TMDL compliance monitoring as well as upstream source investigations in the MSAR (SAWPA, 2016). The MSAR Watershed TMDL Task Force selected the Arlington Area for a Tier 2 Bacteria Source Investigation based on preliminary data collected in PURPOSE To further investigate bacteria sources in the Arlington Area, a Tier 2 Bacteria Source Investigation is being implemented. This study is designed to better understand human sources of fecal contamination and areas contributing dry weather flows. This Study Plan describes Tier 2 Bacteria Source Investigation activities to be implemented in the Arlington Area in fall These activities will be conducted in dry weather (defined as no measurable rainfall in the preceding 7 days). This Study Plan is based on study questions developed with key MSAR Bacteria Indicator TMDL stakeholders, as follows: 1. What are the predominant sources of dry weather flow in the Arlington Area? 2. What is the status of dry weather flow leaving the Monroe Retention Basin? 3. What are the magnitude and sources of E. coli in the observed dry weather flow? 4. Are E. coli from human sources? SAWPA Arlington Tier 2 1 August 2017 Study Plan

149 2 PROJECT ORGANIZATION AND SCHEDULE SAWPA is the lead agency responsible for overseeing the Tier 2 Bacteria Source Investigation in the Arlington Area and coordinating with key stakeholders. Rick Whetsel, the SAWPA Project Manager, has responsibility for overseeing the project work items. City of Riverside and Riverside County Flood Control and Water Conversation District (RCFC&WCD) are main field coordination points of contact. Consultants will conduct dry weather monitoring. Laboratory consultants will conduct constituent analysis. The primary contacts for this investigation are listed in Table 1. Table 1. Points of Contact CONTACT NAME TELEPHONE NUMBER LOCATION OF CONTACT Key Stakeholders for Field Coordination Rick Whetsel, SAWPA Project Manager SAWPA Mike Roberts City of Riverside Kyle Gallup RCFC&WCD Consultants Roshan Christoph, Project Manager Amec Foster Wheeler, San Diego Darcy Ebentier, Project Coordinator/Field Lead Amec Foster Wheeler, San Diego Ted Von Bitner, QA Officer Amec Foster Wheeler, San Diego Cynthia Waddell, Laboratory Project Manager Babcock Laboratories, Inc. James Herrin, Laboratory Project Manager Source Molecular Corporation Amec Foster Wheeler = Amec Foster Wheeler Environment & Infrastructure, Inc.; QA = Quality Assurance; RCFC&WCD = Riverside County Flood Control and Water Conservation District; SAWPA = Santa Ana Watershed Project Authority 2.1 SCHEDULE Table 2 presents tentative project milestones and deadlines for the Tier 2 Bacteria Source Investigation. Table 2. Tentative Project Milestones and Deadlines TASK Kickoff Meeting Desktop Analysis Field Verification Study Plan Draft Study Plan Final Aug 1 Aug 9 Aug 11 TENTATIVE DEADLINE (2017) Au g 18 Aug 30 Sep 7 Sep 12 Flow Source Study (Aug 30 1 to Sep 30) E. coli Source Study (Sep 6 2 to Sep 15) Project Status Report Project Report Draft Project Report Final 1. Assumes SAWPA approval of flow monitoring location selection prior to Study Plan Draft. 2. Assumes SAWPA approval to initiate sample collection prior to Study Plan Final. Sep 30 Nov 17 Dec 22 SAWPA Arlington Tier 2 2 August 2017 Study Plan

150 2.2 CONSTRAINTS Monitoring activities for the Tier 2 Bacteria Source Investigation in the Arlington Area are subject to the following constraints: The study is targeted for dry weather conditions in August and September Should unseasonable rainfall be forecast, monitoring events may be rescheduled. Overlapping of monitoring schedules with downstream Bacteria TMDL 1 compliance monitoring may be impacted by factors that include (but are not limited to) rainfall and staff availability. Field teams will not mobilize during or near the Labor Day holiday. Data collection for the Tier 2 Bacteria Source Investigation in the Arlington Area is subject to the following constraint: Analysis of the human-associated Bacteroides marker HF183 may be affected by inhibition. Inhibition occurs when the enzymatic reaction is slowed or stopped by the presence of inhibitory compounds, often large carbohydrate or humic acid molecules. As a result, inhibition may result in elevated reporting limits or false negatives. Inhibition will be mitigated to the extent feasible by using droplet digital drop polymerase chain reaction (ddpcr) technology and dilution. Matrix spikes and internal controls will be used by the laboratory to assess the level of inhibition for each sampling result. 1 Resolution Amending the Water Quality Control Plan for the Santa Ana River Basin to Incorporate Bacteria Indicator Total Maximum Daily Loads (TMDLs) for Middle Santa Ana River Watershed Waterbodies. Regional Board Resolution R SAWPA Arlington Tier 2 3 August 2017 Study Plan

151 3 STUDY AREA AND SITE SELECTION Based on data collected through 2015, high concentrations of indicator bacteria are originating in runoff from the Arlington Area of the City of Riverside and may flow downstream to the Santa Ana River via the Monroe Retention Basin. Predominant land uses within the Arlington Area are residential and agricultural. Preliminary monitoring suggests that runoff within agricultural lands in the Arlington Area has highly variable levels of bacteria indicators (City of Riverside, 2016). Elevated bacteria levels, however, did seem to be associated with irrigation runoff from nearby orchards (CDM-Smith, 2016). The irrigation water source (Gage Canal) had relatively low levels of bacteria, suggesting that bacteria input occurs after application of irrigation water to orchards (City of Riverside, 2016). Most of the flows southeast (upstream) of Victoria Avenue are transported via earthen channels on both sides of the roadway prior to entering the subsurface storm drain lines that ultimately discharge to the Monroe Retention Basin. Land uses, monitoring locations, and key drainage area details are provided in Figure SITE SELECTION Monitoring locations were selected via desktop analysis and field verification and are provided in Tables 3 and 4. Figure 1 reflects three distinct subdrainage areas (ARL-1, ARL-2, and ARL-3) within the Arlington Area. The following factors were considered during the siting effort. Delineation of areas of agricultural land uses and dry weather flows from residential land uses Key confluences of storm drain lines Flow or evidence of flow was present during field visit If in public right-of-way, safe access and no restricted access or confined space entry Three locations in Don Derr Park (T2-ARL-1, T2-ARL-2, T2-ARL-3) represent most of the dry weather flow that reaches the Monroe Retention Basin from the Arlington Area, from co-mingled agricultural and urban (e.g., residential, commercial) land uses. Land use was a key factor in site selection; majority of sites are selected to support assessment of flow and bacteria sources from agricultural land use. The eight locations in and around Victoria Avenue (T2-ARL-3-IRV, T2-ARL- 3-MON, T2-ARL-2-GRT, T2-ARL-1-ADA, T2-ARL-1-JEF, T2-ARL-1-GRC, T2-ARL-1-MAD, T2- ARL-1-WAS) represent overland flow from predominantly agricultural land uses in the Arlington Area and include most points of entry for agriculture flow to the downstream storm drains within urban land uses in the Arlington Area. The Gage Canal (T2-ARL-GIC) location was selected as a control site to record the water quality in the Gage Canal as it enters the Arlington Area, prior to the water being used for irrigation of agricultural lands. Two additional locations (T1-ANZA and T2-ARL-OUT) will also be used to assess status of outflow from the Monroe Retention Basin to the Santa Ana River. Location T2-ARL-OUT represents the confluence of T2-ARL-1, T2-ARL-2, and T2-ARL-3 as flow exits the Monroe Retention Basin. Location T1-ANZA represents the sum of flows from both the Monroe Retention Basin and other intermediate inputs just prior to discharge to the Santa Ana River. SAWPA Arlington Tier 2 4 August 2017 Study Plan

152 Figure 1. Tier 2 Source Investigation Monitoring Locations and Arlington Area Overview SAWPA Arlington Tier 2 5 August 2017 Study Plan